Metal clad switching unit



Feb. 4, 1936` A M ROSSMAN 2,029,589

METAL CLAD SWITCHING UNIT Filed March 5,1, 195o e sheets-sheet 1 Feb. 4, 1936. A. M. RossMAN 2,029,589

METAL CLAD SWITCHING UNIT Filed March 51, 1930 6 Sheets-Sheet 2 @y WMM/5 Feb. 4, 1936. A. M. RossMAN 2,029,589`

METAL CLAD SWITCHING UNIT Filed March 3l, 193@ 6 Sheets-Sheet 5 l /la4 Fig. /Z

F eb. 4, 1936.

A. M. RossMAN 2,029,589

METAL CLAD SWITCHING UNIT Filed March 3l, 1950 6 Sheets-Sheet 4 /aa/ i /ae /87 /ao /e /a/ /65 /az /5 *1 /4 /4 /aa /aa i@ /3 /5 J /zz/m'or QfQZZefz Mlcggman @y l UMA/- f METAL CLAD SWITCHING UNIT Filed March 5l, 1930 6 Sheets-Sheet 5 Fig. l5

METAL CLAD SWITCHING UNIT Patented Feb. 4, 1936 METAL CLAD SWITCHING UNIT Allen M. Rossman, Chicago, Ill., assignor to Rossman Engineering Company, a. corporation of Illinois Application March 31, 1930, Serial No. 440,606

31 Claims.

This invention relates, in its broad aspects, to electrical power stations and is particularly concerned with novel and improved arrangements for' self-contained switching unit substation equipment suitable for and convertible into the oil filled as well as the air insulated types of equipment for indoor and outdoor service.

The leading aims underlying the invention may be said to reside in the provision of a self-oontained unit equipment which is characterized by simplicity and economy of design of the individual parts and of the entire assembly, with the purpose of increasing the safety to attendants and the reliability of operation by suitably enclosing the various live parts, and thereby also reducing the fire risk; of supplying an arrangement which warrants continuity of service by making the individual parts interchangeable; of decreasing the costs of production and installa- 20 tion while increasing the economy of operation and maintenance; of rendering a unit equipment which requires less floor space than equipment known previously; and, iinally, of furnishing a unit equipment for power distribution stations 25 which may readily be converted from one type of service into another type of service by designing and constructing its parts interchangeable and by standardizing the design of parts for the various types of service so that they may be' re- .30 placed readily by other standardized parts for the same or for other types of service as demanded by circumstances and by individual requirements of an installation.

The desirability of making an electric power 35 distribution center as inexpensive as possible is prompted by the demands for low rates on the part of the consumers and, accordingly, by the necessity to keep the invested capital low. The factors entering into these calculations are well 40 known and need not be discussed in detail.

Local and legal requirements combined demand certain conditions which the equipment must meet. There may be, for example, local technical conditions which would permit the in- 45 stallation of an open type station in a certain locality. Legal requirements, however, governing the safety of operation of electrical equipment, require all conductors, switch gears, and the like, to be housed securely so that no live 50 parts are exposed. This may even necessitate the provision of a sub-station building for housing the equipment properly, and the project of installing' the sub-station may be jeopardized under certain conditions of this character because the expenditures render the undertaking economically prohibitive. l

These and other well known reasons have compelled engineers to devise switching equipment of the so-called metal-clad or armored type, that 60 is to say, equipment in which certain parts are lli Lil

provided permanently in housings 'or otherwise suitably protected and concealed to the outside.

The first solutions took the form of compartments made of masonry. This solved the problem for certain installations, but it was later 5 found that metal-clad equipment, while retaining the desirable features of the masonry structure, presents other features which are recognized as desirable. They are more compact, are easier to install, lend themselves more readily to re- 10 arrangement, and are safer to operate, inspect or recondition.

Such a metal-clad equipment consists of selfcontained switching units, which can be used either singly or as a part of a group to form an entire sub-station.

It will at once be seen that the engineer attempting to devise such metal-clad switching equipment will be confronted with a variety of difliculties. The equipment must suit the purpose and the character of the installation from the engineering and from the operating and maintenance point of View. It must be designed so that it may be produced and installed at a reasonable cost. And it should also be sightly in appearance and compact in character. In short, it should represent a, unitary and exteriorly pleasing structure, easy to manufacture and to install, safe and reliable in operation and maintenance, and constructed with a view to the future requirements which may demand additions to take care of technical and economic growth of a station.

The divers factors intimated above which enter into the calculations of an engineer attempting to design a sub-station for the distribution of electric energy are mutually dependent and the problem is rendered still more diiicult due to `local technical requirements which may differ with each case.

Various attempts at meeting the above conditions have produced rnore or less unitary structures of individual Switching units which, however, offer a variety of objections.

Most of the prior constructions are unsightly in appearance. This is an important factor, since the real estate value of a certain locality may be vitally influenced by the installation of a switching station. If the same is unsightly, the real estate values will depreciate and such installations will be rejected in congested districts. They are usually expensive, which is an important factor, in view of the necessity of economy in invested capital to yield adequate returns. The installation consumes a relatively large amount of money, due to the more or less complex steps required for connecting the various unit assemblies of equipment into one unitary sub-station. Readjustments are carried out only with difculty, necessitating, in most of the prior constructions, complicated procedure of dismounting and remounting.

In order to overcome the above and other objections presented by prior constructions, and in order to meet the divers engineering, legal, and economic requirements satisfactorily, I have designed a novel and improved metal-clad sub-station unit equipment which avoids the disadvantages of prior constructions and incorporates numerous novel features, presenting a unitary and pleasing exterior of utmost flexibility to meet any conditions within reasonable limits of the art.

The invention which I will describe and explain in detail presently, will be better understood and appreciated from a description explaining the successive steps of its development, which I shall now sketch briefly before presenting a detailed description.

I have observed in practice the great difficulties, merely intimated in the previous paragraphs, and have arrived at certain conclusions which iinally matured in the construction of my novel metal-clad unit which I am about to describe.

In the rst place, I found it expedient to think in terms of independent, self-contained units which make a sub-station. These units operate in mutual interdependence. Therefore, means must be provided in each unit to take care of this interdependence of operation. In other words, each unit must be designed to Work as an independent entity if occasion demands, and must also be designed to operate together with other like units as a larger unit of a higher order, in which each individual unit is merely a link in a compact chain.

The fact that prior constructions were always made to order as it Were, and that these prior constructions did not exhibit the standardization of parts compatible with up-to-date requirements of production, suggested a further step, namely, the concept that a sub-station should be compo-sed of a type of units which are not only easily joined in a certain case of installation, but which also lend themselves easily to use as outdoor or indoor equipment, as desired.

In pursuance of this reasoning from the production point of View, and after making various extensive experiments in practice, I arrived at the further conclusion that as many parts as possible should be standardized and made interchangeable to insure economy of production as well as economy of operation and maintenance, and in` order to warrant continuity of service. Should a certain apparatus which is a part of a unit be out of order or withdrawn for readjustments, or repair, the unit holding such apparatus should be so designed as to make it possible to replace the withdrawn part by a like part held in reserve.

Standardization means carefully designed details adapting an article for mass production, reducing overhead cost and equalizlng production' by building for stock and for future demands during dull periods. This principle, applied to power stations, is broadly new, and I am enabled to utilize this principle to advantage by departing from the orthodox concepts taught and practiced in the past in connection with metal-clad switching equipment. l

The various objects which I have accomplished by my invention will now be stated briefly and concisely to guide the understanding of the detailed explanation and of the claims which are to follow:-

It is one object of the invention to design and to construct a compact metal-clad switching unit for power distribution adapted to hold various apparatus, having an independent compartment made of sheet metal for receiving and for holding the bus bars, by utilizing to maximum advantage the limited space that is available without unduly sacrificing clearance or other desirable features, thus providing a bus compartment that may be utilized for a much larger range of capacities than was possible in prior constructions.

Another object relates tol the provision of such a unit in which the current transformers are disposed horizontally in a compartment adjacent the bus compartment, thereby saving space and producing a unitary structure of pleasing appearance.

Still another object is concerned with the provision of a novel connecting device attached to the circuit breaker and adapted to establish connection with stationary terminal studs communieating with the bus compartment, which consists, generally stated, of a device having a flexible tubular member exteriorly surrounded by a coiled spring and adapted to receive a stationary terminal stud which is mounted in insulated relation within a tubular member depending from an intersecting frame plate. The use of this novel connecting device permits considerable decrease in the overall height of the unit.

A further object has to do with the provision of interchangeable panel mountings for receiving relay and switching provisions and adapted to be attached to the unit by bolting.

Another object relates to designing a welded structural steel frame for such a unit adapted to receive and to hold an oil circuit breaker in a simple and efficient manner, avoiding relatively complicated provisions for mounting, and admitting the use of a simple portable elevating truck for securely attaching the oil circuit breaker.

` A further object is concerned with provisions for testing the functions of the oil circuit breaker while in disconnect position, by means of a plug arrangement adapted to be connected to the disconnected circuit breaker and to suitable provisions in the control panel.

Still another object is concerned with provisions disposed between adjacent units of the outdoor type of equipment for catching Water precipitated on the units and for guiding the water downwardly and forwardly, with the purpose of suitably discharging the same.

Another object relates to designing and proportioning all individual casings and enclosures in such a manner that they can be separately made in accordance with the principles of mass production, and easily assembled into a sub-station composed of several units by bolting adjacent units together, joining the bus bars of adjoining units, and coupling together preformed cables and the like, thus reducing the expenses of field construction to a minimum.

A further object resides in designing the several parts of an indoor oil filled metal-clad unit in such a manner that the same may be easily converted into an outdoor oil filled unit by the addition of standardized enclosing details adapted to be attached to the unit without any material alteration.

Still a further object has to do with making the various parts ofY an indoor air insulated type unit, that is to say, the enclosing compartments for the buses and for the current transformers, so that the same may be easily converted into an oil lled unit, either of the outdoor or of the indoor type, by readily making these compartments oil tight by the substitution of standardized parts easily attachable Without altering the unit otherwise.

My invention, in short, represents the rst successful attempt at standardization of power stations. It provides basic structural parts which are the same regardless whether the station is going to be an air type or an oil lled type for outdoor or for indoor service. Attached to the standardized basic parts may be standardized interchangeable enclosing parts which determine the type of station for service and which are of such kind that they permit conversion of a station from one type to another type. The unit which is furnished by my invention is pleasing in appearance and reliable in operation and maintenance. It can be easily assembled with other like units and easily withdrawn for inspection or repair. Each apparatus attached to a unit is easily accessible. The use of an individual mounting provision for locating the oil circuit breaker in place in a unit is rendered superfluous. A common portable elevating mounting truck may be used for attaching to and for withdrawing the circuit breaker from a unit of my construction. 'I'he use of a novel connecting device for joining the circuit breaker with certain terminals in the bus chamber and in the transformer chamber reduces the height of the unit. All parts are protected and supported economically with a view to conserve valuable space and securely with respect to safety of operation and ease of maintenance.

The metal-clad switching unit disclosed in this specification is self-contained and can be used either singly or as a part of a group, to form a totally enclosed, metal-clad switching structure of exceptional electrical and mechanical strength. It affords complete protection to station attendants against accidental contact with live parts. Each unit contains an oil circuit breaker, buses, current transformers, disconnecting devices, and framework completely assembled and wired, ready for installation. The unit is installed by simply locating the same in place, connecting bus sections together where several units are to be joined, insulating the bus joints, making connection to the feeders and to the-'control cables, and, nally, in case of oil-filled units, by lling the compartments with insulating oil.

It will be realized that the features presented by my invention represent valuable advantages which cannot be derived from prior constructions. For example, some of the prior constructions of the most up-to-date types of switching equipment are provided with cast boxes or compartments for holding the bus bars and the current transformers. It will at once be seen that such construction can not furnish the flexibility which I attain by using fabricated compartments. None of the prior constructions provide for such simple and ready assembly of a unit as such and for the eiicient assembly of several units into a group. due to the fact that prior constructions do not realize the necessity and advisability of applying to power stations the principles taught by mass production. None of the. prior constructions presents interchangeability of several individual parts vto adapt a unit for ready conversion from one service type into another service type.

There are several other objects accomplished by my invention which I have not enumerated in the statements of objects or in other general remarks. They will appear as the description progresses.

I will now describe the invention in detail with reference to the accompanying six sheets of drawings which show various modifications of my invention and several detail parts to guide others in the application of the invention to practical use. In these drawings,

Figure 1 shows the rear view of an outdoor oilfilled group consisting of three units of my novel construction;

Figure 2 illustrates a plan top view of the group shown in Figure 1;

Figure 3 represents a side view of the grouped units;

Figure 4 is a partial side view, in cross-section, taken on line 4-4 of Figure 2;

Figure 5 shows the joining of certain parts as seen on line 5-5 of Figure 4;

Figure 6 represents a cross-section through certain parts of the frames and of the enclosures as viewed on line 6 6 of Figure 1;

Figure 7 shows a partial cross-section of the enclosures as seen on line 'I-'l of Figure 3;

Figure 8 corresponds to the view shown in Figure l, representing, however, an indoor oil-lled group and showing certain parts in the interior of the assembled units;

Figure 9 is a top view of the assembly presented in Figure 8 with some of the top covers removed and with certain parts shown in cross-section;

Figure l0 is a side View of a unit of the indoor oil-filled group shown in Figures 8 and 9 viewed on line lll- I0 in Figure 8. Certain parts in this gure are shown removed from the assembly and in cross-section;

Figure 11 shows an interchangeable enclosed panel which may be substituted for the open panel shown in conjunction with the unit presented in Figure 10;

Figure l2 shows a cable provided with plug connections for testing the oil circuit breaker in disconnect position;

, Figure 13 illustrates the front view of an air type group composed of three units;

Figure 14 represents a top view of the group shown in Figure 13 as seen on line lili4 in Figure 13 with the cover of one of the units removed and another unit in partial cross-section;

Figure l5 shows the side view of an air type unit of the group illustrated in Figure 13 as seen on line iti-I5 in this figure; and

Figure 16 represents the cross-section of the novel connecting device for establishing connection between the oil circuit breaker of a unit and .1

the buses and transformers disposed in enclosed compartments on a unit.

`Reierring now particularly to Figures 1, 2 and 13, which represent an enclosed outdoor oil filled group, numerals l, 2 and 3 designate the three `Ii f vertically disposed units assembled to a group as shown. The oil circuit breaker of each unit is disposed within each unit in the lower part thereof, which is completely enclosed by suitable cover plates attached to the frame. portion of each unit contains a terminal chamber section 5, 6 and l, a transformer section 8, 9 and l, a bus compartment ll, l2 and I3, and a switching and control panel compartment I4, I5 and lB, respectively. A manually or motor operated or solenoid operating mechanism is located on the front of each unit under cover marked by numerals l'l, i8 and I9, respectively.

The frame is of welded structural steel, strong and well nished. It includes uprights such as The upper shown in Figure 6 marked by numerals 20 to 21, inclusive, showing the uprights of two adjacent units in cross-section as viewed on line 6 6 of Figure 1. Attached to the ends of a group are end cover plates such as 28, to close a group on the sides. The rear of a group is closed by plates such as 29, 30 and 3| which overlap at the place of joining, as shown in Fig. 6.

The front of the group is enclosed by means of plates such as 32 and 33, and intermediate sections, suoh as 34 and 35 cover the spaces between the uprights of adjacent units as shown in Figure 7.

The cables 3B, 31 and 38, and the outgoing leads I39-4tl, 4|-42, 43-44, are suitably attached to the bottom of the transformer compartments by means of suitable fan pot-heads or terminators 52 and 53, and junction boxes I5-46, I1- 48, and 495|L as is particularly shown in Figure l.

The upper parts of the various compartments are closed by means of suitable cover plates such:

as 54 to 56, and 51 to 59, for the terminal and transformer compartments, respectively. The bus compartments are enclosed similarly, as may be seen from Figure 2.

The individual units are joined by means of flanges (5I- 62, 63-64, 65-66, respectively, which are bolted together, and the ends of the bus compartments of the two end units are closed by means of plates 60 and 61, as shown in Figure 1. It is, of course, understood that suitable packings are provided between the flanges in case of an oil-filled type of unit. v

Switching mechanisms disposed on suitable panels are housed in the compartments I4, I5 and I6, and these housings are attached to the front of each unit by means of flanges Bil- 69, -1I and 12-13, as may be seen from Figures 2 and 3. These anges, although shovm on the outside of the box, could turn inward instead.

Each panel compartment containing suitable relays, etc., as the one designated by numeral I6 in Figure 3, may be provided with a hinged steel door 14 to permit access to the relays or instruments. The panel compartment may also contain control wiring, transformer secondary leads, control buses and solenoid fuses, and other desirable or necessary equipment.

The top plate of each panel compartment projects to the front as shown in Figure 3 and marked by numeral in order to prevent the entry of rainwater.

Rainwater entering between the units as assembled will be caught by strips, such as 16, shown in Figure 4, which slope downwardly and project slightly from the front intersections as is also indicated in Figure 3. The attachment of these diverting strips or troughs to the general structure is particularly shown in Figure 5. It will be seen from this ligure that the sloping trough is securely attached between the individual units, directing rainwater precipitated between the units forwardly and downwardly, guiding the water away from the units and discharging the same.

All parts are factory made, fabricated, standardized to make them interchangeable, and are attached to each other by means of bolts. A perfectly unitary structure, easily produced and assembled is thus achieved, which is more compact than masonry structures, retaining all the advantages that may be rendered by such masonry structure and having additional advantages of great flexibility of production and assembly. Each unit is self-contained and may be easily composed of uprights such as joined to a group with a miniminn amount of expensive field work. A group made up of such units has a pleasing appearance, is more eflicient, safe and compact. All parts are replaceable and easily accessible, thereby providing continuity of service and reliability of maintenance. This example of an oil lled outdoor group, exhibits, it will be appreciated, numerous novel features which .represent an advance in the art of producing and building power equipment.

In Figures 8, 9 and 10, I have shown three views of an indoor oil-filled group, again composed of three units. It will be understood, of course, that neither this nor any other combination of units shown in the drawings and mentioned in this specification is limited to any particular number of units. I have shown a combination of three units assembled to a group merely for convenience of description.

Continuing the explanations, the indoor group shown in the Figures 8, 9 and 10 distinguishes from the outdoor type of assembly described above with reference to Figuresv 1 to 7, inclusive, chiey in the arrangement of the various enclosures. Some of the enclosures, e. g., the cover for the solenoid mechanism, the front and side panels for shielding the frame, the cover for enclosing the relay panel, and the rainwater diverting troughs between the units are not required in connection with the oil-lled indoor type of equipment, and are, accordingly, omitted. All parts, it will be remembered, are standardized and made interchangeable: Ity is, therefore, a relatively easy task to manufacture for stock and to assemble the units suitably for the particular type of service in which they-are needed. Should it become necessary to convert a station from one type into the other, this is easily accomplished by simply attaching or detaching, as the case may be, certain enclosures, adapting the units for the purpose desired. The fact that this is made possible by my invention will readily show its usefulness and the advance which it represents over prior constructions. With the old type construction, a conversion of the equipment from one type into another type of service is quite impossible without costly and material a1- terations.

The Figures 8, 9 and 10 represent three standardized units assembled to a group for outdoor service, and show particularly the arrangement of the various apparatus on the frame and structural details which I will now explain.

Each of the units, 80, 8| and 82 comprises a standardized frame of welded structural steel,

81-88, of cross bars such as 89-90, 9l-92, 93-94, and of brace bars 95, 96 and 91, respectively. Each frame also includes locking bars which may be combined with the cross bars 89, 9| and 93, respectively, for holding the oil circuit breakers in place. The circuit breakers are designated by numerals |0|, |02 and |03, respectively.

The attachment of such a circuit breaker to a unit is accomplished by means of an installing elevating truck on which the circuit breaker is placed for insertion into the. supporting frame or cradle. The front side of each unit frame is open to permit the introduction and removal of the corresponding circuit breaker. The opening is closed by a suitable cover plate when the breaker is in place. The oil circuit breaker is elevated into operating position until the terminals on the circuit breaker engage stationary terminal studs on the intersecting frame plate, closing the bus chamber and the transformer compartment. Only one such portable installing truck is required for a group of units. This is a considerable advantage over known constructions, some of which require individual apparatus for each unit for inserting and for removing the circuit breaker.

The stationary terminal tubes enclosing terminal lugs which communicate with the bus chamber and with the transformer chamber are designated on the drawings (Figure 8) by numerals |04-|05, |06-|01, |08-|09, for the respective units. The structure of these stationary terminals and the structure of the cooperating terminalson the oil circuit breaker will be discussed presently in detail with reference to Figure 16.

The attachment of the cables and the feeders to the various units, by means of suitable potheads, is seen more in detail from Figure 8. Certain detailed information, in addition to the explanations furnished previously in connection with the description of Figures l to 7, inclusive, will be supplied presently.

The manner of assembling the Various units to a group is substantially the same as was explained already. The bus compartments are provided with suitable flanges which are attached to each other1 as shown, by means of inserting between the flanges suitable sealing material or packings for providing a continuous oil-tight channel reaching from the first to the last unit of a group. The iianges ||2 and ||9 of the end units are closed by cover plates, such as and |2|, with packing and |20 interposed between the flanges and the cover plates. The joints between the units, designated ||3| I5, and ||6| |8, are similar in structure. The attachment is by means of suitable bolts.

In Figure 9 is shown a top view of the group. The right-hand unit 82 is shown provided with a cover plate |22 for the terminal end, with a cover |23 for the current transformer compartment, and with a cover plate |24 for the bus compartment. These plates are attached by means of bolts, as already mentioned previously. They permit ready access to theinterior of the various compartments vand furnish eifective protection.

The cables 36, 31 and 38 may be led into the boxes 5, 6 and 1 from above instead of from below. In that event the cover plates such as |22 shown in Fig. 9 cover the openings in the bottom of the boxes 5, 6 and 1 and the bells or cable terminators 52 and 53 are secured over the openings in the tops of the boxes.

The framework of each unit' projects to the front as shown at |25, |26 and |21 on Figure 9. Each of these projecting frame parts bears a flange |28, |29 and |30, respectively, which is provided for attachment of the relay panel housing.

The center unit is shown in Figure 9 with the covers of the various compartments removed to show the interior thereof. The cable sections |3 |32, |33 are shown attached to the horizontally mounted current transformers |34|35 and |36. Connection bars from the disconnecting devices are supported, bolted in place and heavily taped. The other ends of the transformers are connected to these connecting bars, as shown. The arrangement is particularly apparent in the view of the compartment of the left-hand unit, which is shown partially in cross-section. No reference numerals have been applied to the transformers in the left-hand unit because it is thought that the above explanations are sufficiently clear to describe the details without further reference.

The bus bars are disposed in the bus compartments, supported therein by means of suitable supporting bre boards such as the boards |31 and |38 in the left-hand compartment, supporting the buses |38 and |40. As may be seen in Figure 9, the boards |31-I38 extend between the front end |43 of the unit and a metallic partition |44 that divides the unit into two compartments, namely, a bus compartment and a current compartment 8. It is, of course, understood that the buses of every other unit are disposed and supported in the same manner. The bus supports are held against longitudinal displacement by suitable brackets attached to the compartment walls. The junction between buses of adjacent units is made by means of suitable joining bars such as |4| and |42 connecting the buses of the left-hand compartment with the buses located in the center compartment. The buses are connected to the connecting bars from the disconnecting devices and bolted to the buses.

The various connections between the transformers and the disconnecting devices, and between the bus bars and the disconnecting devices, will be apparent with reference to Figure 10, which shows a side view of the left-hand unit of Figure 8 partially in cross-section.

Numerals |45 and |46 designate the uprights of the steel frame. Attached to the upper ends of these uprights are cross supports |1| and |66 holding the bus compartment, the transformer compartment, and the panel compartment. It may be mentioned at this point that the buses, as disposed in the compartment, utilize the maximum .advantage of the available limited rectangular space. There is ample room for four or even more 4" by 1/" bus bars to a phase without unduly sacrificing clearances or other desirable design features. The bus compartments may, therefore, be utilized for a much larger range of capacities than was possible in prior constructions. The clearance between the bus bars and the grounded metal parts, that is to say, between the intersecting supporting plate |65, is about 3". The arrangement, as shown, is very simple as compared with known constructions. It simplies the arrangement and lowers the cost considerably. The clearances which can be held in the construction as discussed permit elimination of hand taping, which would otherwise be required.

Attached to the oil circuit breaker is a. solenoid operating mechanism |41. The breaker may be operated manually or, if desired, motor operated.

There are terminal members, vsuch as |68 and |55, attached to the oil circuit breaker, which are adapted to cooperate with terminal studs mounted within and insulated from the tubular members |61 and |54, attached permanently to the intersecting plate |65 and communicating' with the terminal studs such as |5| and |53 in the bus chamber and in the transformer compartment as shown. The use of this manner of. establishing connection between the circuit breaker and the `buses and the transformers, renders it possible to reduce the overall height of the unit appreciably. This terminal connection will be discussed later on in detail in connection with the description to be furnished for Figure 16.

The buses |56, |51 and |60 are disposed within the chamber as shown, supported by suitable bus supporting plates of insulating material which:75

extend transversely as was described previously in connection with Figure 9. They are joined as shown and connected to the connecting stud |5| as indicated at the stud terminal |63.

'I'he manner of connecting the horizontally mounted transformers is shown in connection with transformer |48, the terminals l|58 and |49 of which are connected to the terminal |52 of the disconnect stud |53 and to the terminal I 50 of the cable |84, respectively. The attachment of the pot-heads of the cable and of the feeders is apparent from the drawings showing one pot-head in cross-section. Covers |11, |18 and |19 close the top openings of the various-compartments. |82 is not a support but a conduit running from connection box |83 to relay panel.

'Ihe junction boxes such as 45, 46, 41, 48, 49 and 50, see Fig. 1, have downwardly extended conduits such as 39, 40, 4|, 42, 43 and 44 for housing low potential leads such as instrument leads, relay leads and the like. The boxes 45, 46,r and the like are connected to the chambers |25, |26 and the like, see Fig. 9, through connecting conduits as shown for example in Figure 10. In this figure the junction box |83, which may be any one of the group, is connected by a conduit to the forwardly extending chamber |25 for providing a suitable housing for instrument or relay leads such as may be connected to the mechanisms |14 and |15 on the instrument panel |13. Suitable insulating oil is introduced through the openings into the bus chambers and, if desired, into the current transformer chambers, and the covers are then securely attached by means of bolts.

The panel compartment may contain relays and suitable control mechanisms. 'I'he rim or flange |12 is provided on this compartment for attaching a front panel |13 provided with switching mechanisms such as indicated at |14 and |15. Although the flange is shown here on the outside, it could turn inward instead. The front panel may be attached to the rim |12 by means of bolts.

When it is desired to insert the oil circuit breaker 0, the same is loaded on a portable truck, mentioned previously, and located within the frame where it is elevated until the terminals |68 and |55 establish connection with the terminals within the tubes |61 and |54, while the terminals |10 establish connection with the terminals |69. The truck is then withdrawn after the locking bars are locked in place, and the unit is now ready for operation.

A substitute control and relay panel is shown in Figure 11. It has a hinged door |16 and may be used in place of the open panel |13.

It may be desirable, for certain reasons, to test the functions of the oilcircuit breaker when the same is in disconnected position, i. e., when the same is withdrawn from the connections as shown in the drawings, Figure 10. This can be done by lowering the oil circuit breaker and by extending the control leads from the panel by means of the exible extension cable provided with connection 1 plugs and |8|, as shown in Figure 12. One end of the test couple is in such case attached to a socket |69 in the control panel and the other plug is attached to terminals of the oil circuit breaker control leads.

It will be seen from the above description of the oil-filled unit designed for indoor service and from the preceding description of the oil-lled unit for outdoor service, that the two units have a number of essential features in common. A maximum number of details is standardized and interchangeable. The parts are fabricated and simplybolted together. It is, therefore, possible to convert a unit from an outdoor to an indoor service without any trouble or alteration of essentials. The production, it will be appreciated, is simplified to the utmost extent by the standardization which I have provided for this type of equipment, and installation is equally simplified since the fieldwork necessary for installing the units is reduced to bolting factory made units together.

I have applied the same principles evidenced in case of the above described equipment to the air insulated type of switching unit which is shown in the drawings Figures 13, 14 and 15. Many of the details are now known from the previous discussion and I shall therefore limit the explanations with reference to the air insulated type of unit to those features which diier from what has been explained already.

The units shown in Figures 13, 14 and 15 again comprise a framework 0f standardized design which can be employed for any type of service.

The various apparatus are essentially attached in a manner identical to the manner explained previously. The difference appears in the mode of enclosing the units and the equipment within each unit, as well as in the mode of assembling a number of units to make a group. There is no provision for oil-tight enclosures necessary in case of an air insulated equipment, and, accordingly, the design is somewhat simpler Fabricated boxes having compartments furnishing partitions or sections for the reception of the buses, of the transformers and of other equipment, are provided, and the covers for the bus compartments have aring extensions such as shown in Figures 13 and 14 and designated |85, |86 and |81, reaching over the cover of an adjacent unit and holding the units together by bolts attached through these flaring extensions. The ends of a group are provided with protecting covers such as |88 and |89. The relay and control panels are provided with hinged doors |90, 9|

and |92, respectively, permitting access to the y interior of each panel. It may be desirable to mount certain control or switching equipment on the outside of the panel door as is indicated in Figure 15 by numerals |93 and |94.

Other details are essentially the same as discussed previously. They appear clear from the drawings, since the equipment is standardized, and will be understood without further explanations.

It will be understood, of course, that all parts shown on the drawings, Figures 13, 14 and l5, are

similarly standardized and made interchange- Numeral 200 designates an intersecting frame plate, such as the one designated by numeral |65 of Figure 10. Attached to this plate by means of bolts 20| and 202 is a bushing 203 also holding the tubular member 204. The end of this tubular member is closed at 205 and holds an .insulating tube 206. Inside the latter is a threaded support ring 201, having rounded edges and holding atubular member 208 to whichis attached a closing ring 209 which holds the terminal stud or finger 2I0. The latter is in permanent contact with a bus terminal or with a terminal of a transformer, respectively, as explained previously. The tubular member 208 is insulated from the outside shell members by means of tubular spacing members 2I I, 2I2, and 2I3 of-insulating material.

By this construction the stationary terminal 2 I0 and its supporting ring 209 are elevated above the frame plate 200 of the bus housing, thereby providing ample creepage and striking distances between the'terminal and the grounded plate 200. This elevation does not require a corresponding increase in the height of the structure as this terminal occupies the fourth corner of the rectangular shaped bus housing, the other three corners of which are occupied by the bus conductors. The stationary stud connector 2I0 is located within the hollow insulating support and as close as possible to the terminal connection to the bus conductor. Thus when the circuit breaker is in normal operating position, the connector on the terminal post 2I4 is within the cross sectional area of the bus housing. Hence, all available space in the bus housing is utilized with greatest efiiciency and with a maximum of safety.

The stud 2 I4 is attached to the circuit breaker in suitable and known manner. Upon the stud 2M there is mounted a suitable tubular expansible socket of a novel construction. The socket preferably consists of a number of sections of cast or rolled copper or the like forming jaws 2I8, for example four in number, which are dared out at their upper ends to receive the stud 2l!) and are machined or pressed to approximately a cylindrical inner contour for engaging the stud 2III. These jaws 2I4 are grooved on their outer peripheries to receive encircling helical springs 2I9 for contracting the jaws all towards a common center. The lower ends of the jaws are mechanically connected to an adapter 2I6 through the medium of a ring 2 I9'. This ring is coupled relatively loosely to the adapter 2I6 by a single bolt 220 extending through axial openings in the ring 2 I 9 and the top of the adapter 2 I6, which adapter is in the shape of an inverted cup, the open end of which threads onto the threaded portion 2I5 of the stud 2I4 and is held in place by a set screw or grub screw 2I1. The hole in the ring 2I9 is larger than the bolt 220 to permit lateral play for the purpose of permitting the entire socket to be translated to adapt it to slight variations in spacing of the stud 2H). The ring 2I9 has pins 22I extending radially therefrom and passing relatively lsely through holes in the lower ends of the jaws 2T8. The jaws 2I8 are electrically connected to the adapter 2I6 by flexible braids 222. These braids have their ends folded back and attached tc the Jaws 2I8 and to adapter 2I6. The upper ends arc turned inwardly and downwardly to lie against the outside of the jaws 2I8 and are riveted thereto. The lower ends of the braids 222 are turned inwardly and upwardly and secured at against the outside surface of the adapter 2 I 6. A strap or winding of wire 222 to facilitate soldering or the like may encircle the lower ends of the braids 222 to bind them upon the adapter 2 I6. This construction is highly advantageous as it provides a exible socket for connections of this character of unusual short axial length. The jaws which are separated from each other are readily secured to the braid as by riveting as shown, when the same are turned through substantially 180 from the position shown. The ease with which the jaws may be repaired or replaced is apparent. Likewise the manner of securing the lower ends of the braid 222 to'the adapter 2 I6 will be apparent, namely; that the braids are swung around the lower bends through substantially 180 from the position shown in Fig. 16 and when the braids are in this position the lower ends are exposed and are readily attachable to or removable from the adapter. When the parts are assembled as shown in Fig. 16 by swinging the braids with the attached jaws upwardly the joints between the braids and the connected pieces are covered by the braids themselves, and a maximum length of flexible braid is provided with a minimum overall length of the entire structure. This arrangement is highly advantageous and constitutes an important improvement.

The connecting device described above presents a number of novel features, e. g., the laterally i flexible braid connection and the radially ilexible tubular connector. By using this terminal, it is possible to reduce the overall height of the unit appreciably, gaining valuable space without in any manner impairing the reliability of operation. As a matter of fact, the reliability of operation is increased by the use of this novel terminal.

It will be seen from the above explanations that I have devised a sub-station unit having various advantages over what is known in the art of making sub-stations for the distribution of electric energy. My invention makes it possible to simplify and to equalize production by standardization of parts; to simplify installations; to produce a unit of this character which retains all the advantages of known equipment and which has additional advantages over and above what is known, requiring less iioor space, presenting a pleasing appearance, and readily lending itself to conversion to other types of service.

I refer herein to the units as standardized and interchangeable. By this I mean that the units have the same dimensions in respect to such parts as determine the working dimensions for joining one part to another. Like parts for the units are interchangeable and likewise are standardized, that'is, made to the same working dimensi-ons. are the same for either indoor or outdoor use, and these parts are therefore, to that extent, standard parts in that they enter into the oonstruct-ion of a station whether intended for one type of service or another. The same is true in respect to whether the compartments are oil-filled t or merely air insulated.

I am, of course, aware that numerous modications may be devised, changing the details of the embodiments of the invention :is shown and described without altering the spirit and the essence of the invention. I therefore desire it to be understood that what I have described and shown represents embodiments ior the purpose ing electric energy, having a vertically disposed fabricated frame structure, an oil circuit breaker Certain of .the parts of my stationl removably mounted within said structure, a plurality of bus bars, switching and control equipment, stationary circuit connections, and fabricated sheet metal enclosures disposed on said frame structure for enclosing said bus bars, said equipment and said circuit connections, and for determining said unit for dielectric-filled outdoor or indoor service or for air insulated service.

2. A self-contained switching unit for distributing electric energy, having a vertically disposed frame structure, a circuit breaker removably mounted within said structure, a plurality of bus bars, a plurality of horizontally disposed current transformers, switching and control equipment, stationary circuit connections, and fabricated bolted sheet metal sections forming compartments and enclosures for enclosing said apparatus and equipment disposed on said frame structure and for determining the service type o1 unit when assembled upon said frame structure.

3. A self -contained switching unit for distributing electric energy, having a vertically disposed fabricated frame structure, a circuit breaker removably mounted within said structure, a plurality of bus bars, a plurality of current transformers, switching and control equipment, stationary circuit connections, all supported by said frame structure, connecting devices for maintaining connection between said circuit breaker and the apparatus and equipment supported by said frame structure, and fabricated removable sheet metal enclosures for enclosing said apparatus and equipment disposed on and supported by said frame structure and for determining said unit for oil-filled outdoor or indoor service or for air insulated service.

4. A self-contained switching unit for distributing electric energy, having a vertically disposed fabricated frame structure, an oil circuit breaker removably mounted within said structure, a plurality of bus bars, a plurality of current transformers, switching and control equipment, stationary circuit connections, all supported by said frame structure, connecting devices for maintaining connection between said circuit breaker and the apparatus and equipment supported by said frame structure, and fabricated sheet metal sections forming compartments and enclosures for receiving said apparatus and equipment disposed on and supported by said frame structure and for determining the service type of said unit when assembled upon said frame structure.

5. Metal-clad switching equipment for the distribution of electric energy, comprising a plurality of vertically disposed self-contained independent units each containing a plurality of standardized apparatus and equipment assembled for operation, fabricated standardized sheet metal enclosures for each of said units assembled in place on each unit by means of bolting for enclosing the apparatus and equipment of each unit and for determining each unit for oil-filled outdoor 01 indoor service or for air insulated service, respectively, additional service type determining standardized enclosures for attachment intermediate of adjacent units, and means on certain of said enclosures of each unit for joining adjacent units by means of bolting.

6. A self-contained switching unit for the distribution of electric energy, having a vertically disposed standardized fabricated frame structure containing a plurality of standardized operating apparatus and control equipment assembled for operation, and standardized fabricated interchangeable sheet metal enclosures assembled on said unit for enclosing said apparatus and said control equipment and for determining said unit for oil-filled outdoor or indoor service or for air insulated service.

7. Metal-clad switching equipment for the distribution of electric energy, comprising a plurality of vertically disposed self-contained units each composed of a vertically disposed standardized frame structure containing a plurality of standardized operating apparatus and control equipment assembled for operation, standardized metal sheet enclosures composed of interchangeable sections removably secured in place for enclosing the apparatus and control equipment on each unit and for predetermining each unit for a certain service type convertible into another service type by assembling different standardized metal sheet enclosures on each unit, additional service type determining standardized enclosures for attachment to said units intermediate thereof, and means on certain of said enclosures of each unit for rmly coupling adjacent units.

8. In metal clad switch gear the combination of unit structures each comprising a fabricated metal frame open at its front, stationary terminals disposed within the upper end of the frame, a circuit breaker mountedwithin the frame and removable through said opening, said circuit breaker having terminals and being adapted to be raised and lowered within the frame to connect and disconnect the same from said stationary terminals, a tubular bus housing section supported on the frame and having attaching means for forming a fluid-tight joint with an adjacent section, said section being generally rectangular in cross-section, three bus phase conductors disposed in three corners of said section, corresponding terminal posts extending into the fourth corner and being connected to the bus phase conductors, said posts extending downward outside the bus housing section for connection with the said stationary terminals, and a terminal chamber back of the bus housing section having terminal posts extending down outside the chamber and connecting with said stationary terminals, and line conductors entering the terminal chamber and being connected to said last named terminal posts.

9. In metal clad switch gear a unit section comprising a hollow supporting frame having a circuit breaker within said frame mounted for raising and lowering and being removable through the open side of the frame, said circuit breaker having slip terminals, a tubular bus housing section supported on the frame and having attaching means for forming a fluid-tight joint with an adjacent section, bus phase conductors disposed in said housing section substantially at three corners of a rectangle, terminal posts spaced from each other and disposed substantially at the fourth corner of the said rectangle and being disposed in alinement with each other, tap conductors extending from said posts to said bus phase conductors internally of said rectangle, a lrst group of stationary slip terminals below said housing section for cooperation with the corresponding slip terminals of the circuit breaker and being connected to the terminal posts within the said housing section, a terminal chamber adjacent the housing section, a second group of slip terminals having terminal posts in the terminal chamber and being adapted for cooperation with the corresponding slip terminals of the circuit breaker, and a line connected to said latter terminal posts.

10. In metal clad switch gear a unit section comprising a hollow supporting frame having a circuit breaker within said frame mounted for raising and lowering and being removable through the open side of the frame, said circuit breaker having slip terminals, a tubular bus housing section supported on the frame and having attaching means for forming a fluid-tight joint with an adjacent section, bus phase conductors disposed in .said housing section substantially vat three corners of a rectangle, terminal posts spaced from each other and disposed substantially at the fourth corner of the said rectangle and being disposed in alinement with each other, tap conductors extending from said posts to said bus phase conductors internally of said rectangle, a rst group of stationary slip terminals below said housing section for cooperation with the corresponding slip terminals of the circuit breaker and being connected to the terminal posts within the said housing section, a terminal chamber at one side of the housing section and arranged for top or bottom connection with a cable end bell, a second group of slip terminals having terminal posts in the terminal chamber and being adapted for cooperation with the corresponding slip terminals of the circuit breaker, current transformers disposed in said terminal chambers and connected to said last named posts, and a line having an end bell joined to said terminal chamber and having its conductors joined to said current transformers.

11. In metal clad switch gear a unit section comprising a hollow supporting frame having a circuit breaker within said frame mounted for raising and lowering and being removable through the open side of the frame, said circuit breaker Ahaving slip terminals, a tubular bus housing section supported on the frame and having attaching means for froming a fluid-tight joint with an adjacent section, bus phase conductors disposed in said housing section substantially at three corners of a rectangle, terminal posts spaced from each other and disposed. substantially at the fourth corner of the said rectangle and being disposed in alinement with each other, tap conductors extending from said posts to said bus phaseconductors internally of said rectangle, a first group of stationary slip terminals below said housing section for cooperation with the corresponding slip terminals of the circuit breaker and being connected to the terminal posts within the said housing section, a terminal chamber at one side of the housing section and arranged for top or bottom connection with a cable end bell, a second group of slip terminals having terminal posts in the terminal chamber and being adapted for cooperation with the corresponding slip terminals of the circuit breaker, current transformers disposed in said terminal chambers and connected to said last named posts, a line having an end bell joined to said terminal chamber and having its conductors joined to said current transformers, and a control box at the side of the housing section opposite the terminal chamber having control mechanism for the circuit breaker, said circuit breaker having operating mechanism provided with a slip connection with said control mechanism, said last named slip connection being operable simultaneously with the aforesaid slip terminals of the circuit breaker.

12. In metal clad switch gear a unit section comprising a hollow supporting frame having a circuit breaker within said frame mounted for raising and lowering and being removable through the open side of the frame, said circuit breaker having slip terminals, a tubular bus housing section supported on the frame and having attaching means for forming a fluid-tight joint with an adjacent section, bus phase conductors disposed in said housing section substantially at three corners of a rectangle, terminal posts spaced from each other and disposed substantially at the fourth corner of the said rectangle and being disposed in alinement with each other, tap conductors extending from said posts to said bus phase conductors internally of said rectangle, a first group of stationary slip terminals below said housing section for cooperation with the corresponding slip terminals of the circuit breaker and being connected to the terminal posts within the said housing section, a terminal chamber at one side of the housing section and arranged for top or bottom connection with a cable end bell, a second group of slip terminals having terminal posts in the terminal chamber and being adapted for cooperation with the corresponding slip terminals of the circuit breaker, current transformers disposed in said terminal chambers and connected to said last named posts, a line having an end bell joined to said terminal chamber and having its conductors joined to said current transformers, a control box at the side of the housing section opposite the terminal chamber having control mechanism for the circuit breaker, said circuit breaker having operating mechanism provided with a slip connection with said control mechanism, said last named slip connection being operable simultaneously with the aforesaid slip terminals of the circuit breaker, and a test cable having slip connections for joining the slip con:- nections of the control mechanism to the slip connections of the operating mechanism when the circuit breaker is lowered and disconnected for testing the operation of the circuit breaker.

13. In metal clad switch gear a tubular housing section substantially rectangular in cross-section, bus phase conductors disposed in the two upper and one lower corner of the rectangle and spaced from the walls of the chamber, three insulated terminal posts disposed in alinement in the fourth corner of the rectangle and extending outside the casing section, and short tap connections extending from said terminal posts within the figure dened by said bus conductors and terminal posts, whereby said tap connections do not approach the walls of the housing section.

14. In metal clad switch gear a tubular housing section substantially rectangular in cross-section, bus phase conductors disposed in the two upper and one lower corner of the rectangle and spaced from the walls of the chamber, three insulated terminal posts disposed in alinement in the fourth corner of the rectangle and extending outside the casing section, and short tap connections extending from said terminal posts within the figure defined by said bus conductors and terminal posts, whereby said tap connections do not approach the walls of the housing section, said housing section being fabricated of sheet metal and having a removable top wall to permit of access to the interior of the same, and there being joining flanges at the ends of the housing section for making a fluid-tight joint with adjacent housing sections.

15. In a device of the class described, the combination of a frame section, an open ended bus housing section supported thereby, a circuit breaker supported in the frame section below the bus housing section and having terminals,

connections from the terminals of the circuit breaker extending into the bus housing section and formingterminal posts, transversely extending plates of insulation in the bus housing section on opposite sides of the terminal posts, bus bar sections lying within the bus housing section and projecting through and being supported by said plates at three corners of a rectangular gure, said terminal posts being disposed at the fourth corner of the rectangular figure, and connections between said terminal posts and the bus bar sections.

16. In metal clad switch gear, a tubular bus housing of substantially rectangular cross section supported on a vertical frame, three bus conductors disposed in the two upper and one lower corner of said housing, three terminal posts connected to said bus conductors by short tap connections, said terminal posts being supported on hollow insulating supports disposed in alignment in the fourth corner of the bus housing, slip terminals Within said supports connected to said terminal posts, a circuit breaker disposed below said bus housing and within said vertical frame and having terminal posts provided with connectors adapted for cooperating with said slip terminals.

17. In a device of the class described, the combination of a vertically disposed frame section, a fabricated bus housing section supported thereby, a circuit breaker supported in said frame section below the bus housing section and having upwardly extending terminal posts provided with slips connectors, bus bar sections disposed in the two upper and one lower corners of the bus housing section, terminal posts connected to said bus bar sections supported on hollow insulating supports disposed in the fourth corner of the bus housing and extending through to slip terminals within said hollow supports and cooperating with corresponding circuit breaker slip connectors, a fabricated terminal chamber adjacent to said bus housing, a second group of hollow insulating supports, each having terminals for connecting to an incoming line, and slip terminals within said hollow: supports adapted for cooperation with corresponding slip terminals of the circuit breaker.

- 18. A metal clad switching unit comprising a hollow fabricated frame structure, a circuit breaker removably mounted within said structure and having upwardly extending terminal posts provided with slip connectors, a tubular bus housing of substantially rectangular cross section fabricated of a non-brittle metal and supported on said frame structure, three bus conductors disposed in said bus housing, each conductor occupying one corner of said housing, terminal posts connected to said bus conductors by short tap connections, said terminal posts disposedA in alignment in the fourth corner of the bus housing and supported on hollow bell shaped insulating supports, said terminal posts extending through to slip terminals within said hollow supports cooperative with said slip connections on said circuit breaker, a terminal chamber adjacent to said bus housing, said chamber being fabricated of a non-brittle metal, a second row of terminal posts within said chamber, said posts cooperating with corresponding terminal posts on the circuit breaker, current transformers horizontally disposed within said terminal chamber and connected to said terminal posts, said terminal chamber having openings in the top and bottom thereof provided with interchangeable cover plates for bringing in power line conductors for connection to said current transformers, and means for attaching fabricated sheet metal enclosures to said frame structure for enclosing said equipment and for determining said switching unit for outdoor or indoor service.

19. In metal clad switch gear, a frame, bus and terminal sections mounted on said frame and having a wall separating said sections, terminal posts in said sections, a circuit breaker disposed in said frame below said sections and h'aving terminals vertically movable to engage the terminal posts of said sections, and three bus bars disposed adjacent three respective corners of said bus section and connected to the terminalposts of said section. Y

20. In metal clad switchgear, a tubular bus housing of substantially rectangular cross section, three bus conductors and a row of terminal posts disposed in said housing, each conductor being located adjacent to one corner of the housing and said terminal posts occupying the fourth corner of said housing.

21. In metal clad switchgear of the class described, a tubular bus housing, a plurality of bus conductors of different phase circuits extending longitudinally through said housing, a circuit breakerrdisposed below said housing, said circuit breaker having upward extending connectors vertically movable to connected and disconnected positions, and means for receiving said connectors into said bus housing and for establishing contact with said buses.

22. In metal clad switchgear of the class described, a tubular bus housing, a plurality of bus conductors of diierent phase circuits extending longitudinally through said housing, a. circuit breaker movable vertically to connected and disconnected positions disposed below said housing, said circuit breaker having upward extending terminal posts, each post having a connector, and stationary terminal connectors connected to said bus conductors, said stationary connectors being mounted within the housing on hollow insulating supports, said circuit breaker terminals in normal operating position extending within the cross sectional area of the housing and making contact with said stationary connectors.

23. In metal clad switchgear, a tubular bus housing, a plurality of bus conductors of different phase circuits extending longitudinally through said housing, stationary terminal connectors connected to said conductors, a circuit breaker below said housing, said circuit breaker being movable vertically to connected and disconnected positions and having upward extending terminal posts, each post having a connector adapted for co-operation with said stationary connectors, said stationary connectors mounted in the bus housing and supported within hollow insulating supports at such an elevation that the circuit breaker connectors when in normal operating position extend above the plane of the bottom of the tubular bus housing.

24. In metal clad swtchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure mounted on and overhanging said frame comprising a unitary sheet metal housing having disposed on opposite sides of said partition for coacting with said movable disconnecting contacts through the lower walls of sai-d compartments, and supporting means for said feeder cable connections mounted in the overhanging bottom wall structure of said housing.

25. In metal clad switchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure mounted on said frame comprising a unitary sheet metal housing having an isolating partition for dividing the same into compartments, one of said compartments housing bus bars and the other of said compartments housing current transformers and feeder cable connections, disconnecting contacts disposed on opposite sides of said partition for coacting with said movable disconnecting contacts through the lower walls of said compartments, and supporting means for said feeder cable connections mounted in the wall structure of said housing.

26. In metal clad switchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure on said frame comprising a shatterproof housing having an isolating partition for dividing the same into compartments, one of said compartments housing bus bars and the other of said compartments housing current transformers and feeder cable connections, and disconnecting contacts disposed on opposite sides of said partition for coacting with said movable disconnecting contacts through the lower walls of said compartments.

27. In metal clad switchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure mounted on said frame comprising a unitary housing formed of shatterproof sheets and having an isolating partition for dividing the .same into compartments including a bus bar compartment, said compartments having apertures in the bottom wall thereof on opposite sides of said partition and said bus bar compartment provided with openings at opposite ends thereof for extending the bus bar circuit, and insulating shields supporting fixed disconnecting contacts having contact surfaces extending above the bottom wall of said compartments, said shields comprising insulating tubes mounted in and extending through said apertures, said xed disconnecting contacts being connected to bus bars in said bus bar compartment and to electrical conductors in another of said compartments.

28. In metal clad switchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure mounted on said frame comprising a shatterproof housing having an isolating partition for dividing the same into compartments including a bus bar compartment, said compartments having apertures in the bottom wall thereof on opposite sides of said partition and said bus bar compartment provided with openings at opposite ends thereof for extending the bus bar circuit, and insulating shields supporting xed disconnecting contacts engageable by the movable contacts, said movable contacts extending through said apertures when the fixed contacts are engaged by the movable contacts, said xed disconnecting contacts being connected to bus bars in said bus bar compartment and to electrical conductors in another of said compartments.

29. In metal clad switchgear including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, a superstructure mounted on said frame comprising a unitary sheet metal housing having an isolating partition for dividing the same into compartments including a bus bar compartment, said compartments having apertures in the bottom wall thereof on opposite sides of said partition, and insulating shields supporting fixed disconnecting contacts having contact surfaces disposed above the bottom wall of said compartments, said shields comprising tubes of insulation mounted in and extending through said apertures, said xed disconnecting contacts being connected to bus bars in said bus bar compartment and to electrical conductors in another of said compartments.

3G. Superstructure for metal clad switchgear vof the drop-down type including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, comprising a unitary sheet metal housing having a metallic isolating partition for dividing the same into a bus bar compartment and a current transformer compartment, fixed disconnecting contacts disposed in each of said compartments and in registry through apertures in the bottom walls of said compartments with said movable disconnecting contacts, said bus bar compartment having apertures in the side walls thereof for permitting inspection and extension of the bus bars therein, removable cover members for said apertures, and removable cover structure forming part of the top of said housing for-permitting access to both of said compartments including the connections to the fixed disconnecting contacts and for premitting access to the current transformers and connections thereto in said transformer compartment.

31. Superstructure for metal clad switchgear of the drop-down type including a supporting frame and a switch unit having disconnecting contacts vertically movable therein to connected and disconnected positions, comprising a shatterproof housing having an isolating partition for dividing the same into a bus bar compartment and a current transformer compartment, fixed disconnecting contacts disposed in each of said compartments and in registry through apertures in the bottom walls of said compartments with said movable disconnecting contacts, said bus bar compartment having apertures in the side walls thereof for extension of the bus bars therein, and removable cover structure forming part of the top of said housing for permitting access to both of said compartments including the connections to the xed disconnecting contacts and for permitting access to the current transformers and connections thereto in said transformer compartment.

ALLEN M. ROSSMAN. 

